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Biomedical subjects

J T Bonner

Publications and source records attributed to J T Bonner.

At least 55 records · Page 3Linked to original sources
PubMed1970

Induction of stalk cell differentiation by cyclic AMP in the cellular slime mold Dictyostelium discoideum.

Cyclic AMP, which is a cell attractant (acrasin) for Dictyostelium discoideum, will cause isolated, unaggregated cells to turn directly into stalk cells containing thick celluloselike walls and large vacuoles. From previous work we know that in the cell mass, acrasin is produced solely in the region of stalk formation during fruiting, that stalk formation involves a high level of catabolism, and that cyclic AMP stimulates catabolic enzymes in other systems. These facts obviously suggest that in the development of D. discoideum, cyclic AMP might be a key factor in stalk cell differentiation.

Adenine Nucleotides↗
PubMed1970

Evidence for a second chemotactic system in the cellular slime mold, Dictyostelium discoideum.

An unknown substance found in bacteria (Escherichia coli) is especially effective in attracting the vegetative amoebae of the cellular slime mold, Dictyostelium discoideum. However, the aggregating amoebae are not attracted to it at all. On the other hand, the vegetative amoebae show very little chemotactic response to cyclic adenosine monophosphate (cyclic AMP), whereas the aggregating amoebae are exceptionally responsive to it. It is suggested that the new factor may be used in food seeking, whereas cyclic AMP, the chemotactic substance responsible for aggregation, is the acrasin of this species. The important point is that the amoebae are differentially stage-specific in their responses to these two chemotactic agents.

Biological Products↗
PubMed1969

Identification of adenosine-3',5'-monophosphate as the bacterial attractant for myxamoebae of Dictyostelium discoideum.

Adenosine-3',5'-cyclic monophosphate was shown to be the compound found in Escherichia coli responsible for the attraction of the amoebae of the cellular slime mold Dictyostelium discoideum. A number of other nucleotides were tested and the following were active: tubercidin-3',5'-cyclic monophosphate, N(6)-2'-O-dibutyryl-adenosine-3',5'-cyclic monophosphate, 5'-methylene adenosine-3',5'-cyclic monophosphonate, guanosine-3',5'-cyclic monophosphate, uridine-3',5'-cyclic monophosphate, cytidine-3',5'-cyclic monophosphate, inosine-3',5'-cyclic monophosphate, and thymidine-3',5'-cyclic monophosphate. They were less active than adenosine-3',5'-cyclic monophosphate. It is suggested that cyclic adenosine monophosphate secreted by the bacteria is used by the amoebae as a means of sensing and orienting towards food.

Adenine Nucleotides↗
PubMedDate not supplied

Behavior of cellular slime molds in the soil.

Cellular slime molds are soil organisms, yet since they were discovered in 1869 they have been studied on agar surfaces. Here the behavior of a number of species is examined and it is evident that they have different responses to directional light and they all thrive in the presence of soil. While phototaxis clearly plays a significant role in their ability to come to the soil surface for dispersal, even more important are gradients in the soil: both temperature gradients known from earlier studies, and as we show here gas gradients, presumably ammonia as a repellent and oxygen as an attractant. There are numerous differences in both morphology and behavior among slime mold species, some of which are likely to be the result of natural selection to particular habitats, while others could be explained more easily by neutral phenotypic variation.

Animals↗